Disc brakes for automobiles and other vehicles include a metallic disc or rotor on the axle of the vehicle positioned adjacent the wheel mounting, the faces of which are gripped by a friction material to brake the rotation of the wheel. After periods of excessive use, disc brake rotors wear unevenly such that annular ridges are worn into the surface of the metal around the perimeter of the rotor. The ridges detract from the proper operation of the brakes and, therefore, when the wear has become excessive, the faces of the rotor are subjected to a machining operation which removes metal and leaves the faces smooth and parallel to each other. The machining process may be accomplished by removing the rotor from the vehicle and attaching it to a rotatable member. A pair of tools securely mounted adjacent the edge of the rotor are then moved along the two faces of the rotor while it is rotating to shave off sufficient metal to leave the remaining surfaces smooth. As an alternative, mountings are available which hold the tools adjacent the opposite sides of the rotor while the rotor is mounted on the vehicle. A separate motor rotates the rotor such that the rotor can be machined without removing it from the vehicle.
In either of the two processes described above, the rotor and tools have a tendency to vibrate during the machining operation and such vibrations can be extremely noisy, and the vibration may result in unevenness of the surface of the faces of the rotor after machining and thereby reduce the effectiveness of the machining operation. To reduce such vibration, it has become common to attach to the support mechanism holding the tools, a vibration dampening device, typical examples of which are shown by U.S. Pat. Nos. 3,710,661 and 4,531,434.
Prior art dampening devices have generally provided arms which attach to the tool mounting element, such as shown in U.S. Pat. No. 3,710,661 or as an alternative, consist of two long arms which are retained in position by resting them against the tool mounting mechanism as shown in U.S. Pat. No. 4,531,434. In many cases, however, the tool supporting member is not adapted to attach a dampening device such as shown in U.S. Pat. No. 3,710,661. Also, prior art dampening devices having a pair of long arms which rest upon the upper surfaces of the tool mount and therefore are not physically adaptable for use with certain machines intended to resurface rotors mounted on the vehicle and also block the positioning of a protective shield provided certain machines which are intended to prevent shavings from being tossed into the face of an operator. As a result, none of the existing dampening devices can be sold as original equipment for certain machines because the machines cannot be operated safely with the dampener attached and the use of the dampener would violate certain United States safety standards under the existing federal laws.
The present invention is intended to provide a dampening device which can be used with many existing lathes, including those which machine the surfaces of rotors while on the vehicle and those which machine the surfaces of a rotor removed from a vehicle without interfering with the use of the protective shield adaptable for use with such machines.